The Effect of Height of Structure on the Accuracy of Nonlinear Static Analysis Methods in Steel Structures with Lead Rubber Bearing (LRB) Base Isolators

Abstract

In this study, a comparative study of non-linear static methods with time history method for Chevron braced structures (with LRB seismic base isolator at the base level) is performed. To find out the effect of the building's height on seismic responses of isolated structures, in this study 3 isolated building structures by LRB isolators with 3 different number of stories of 4, 7 and 10, located in a high seismicity area have been modeled in 3D by assuming the soil type C. Pushover non-linear static analysis procedures, with target displacements according to ASCE41-13 code and using three lateral load patterns, including structure's first mode, uniform and triangular have been analyzed using spectral dynamic, PSC and the results have been compared with those of non-linear dynamic analysis subjected to selected far-field earthquakes. The results show that in the estimation of maximum displacement of LRB isolators and also the amount of base shear, ASCE41-13 has a high degree of accuracy in structures with different heights. In estimating the displacement of maximum floors, first mode methods, uniform, spectral dynamic have had enough accuracy in all discussed heights. In estimating the relative displacement of structures' floors, by increasing the height of the structure, the accuracy of the triangular load's pattern reduces significantly. In contrast with it, the PSC method has high accuracy.